It is well-known in the art of high-fidelity and stereo recordings that the overall quality of the reproduction of sound signals obtained from a source such as, magnetic tape, a record, etc., may be enhanced in certain situations (e.g., low listening levels) by raising the level of those signals having frequencies within the so-called bass region. However, the designers of telecommunications systems have heretofore taken an opposite approach and have purposely discriminated against speech signals residing in the bass region, thereby degrading the overall quality of speech signals that are delivered to an intended destination, e.g., a telephone station set.
The reason for such discrimination is that surveys show that the predominant sources of ambient (background) noise have most of their energy in the low frequency range. Accordingly, to prevent a telephone station set that is in use from "picking up" such noise, the station set transmitter is designed so that it noticeably attenuates signals below 300 Hz. In fact, the Electronic Industries Association (EIA) standard RS-470, published January, 1981, and relating to the design of telephone instruments recommends such attenuation below 300 Hz. What this means is that the quality of voice signals that are received at a telephone station set is noticeably diminished as a result of severely attenuating the level of such signals below 300 Hz at the transmitting telephone station set.